TO:  All GCN Notice recipients
RE:  Day-of-Week Time-of-Day Notice added
DT:  13 June 11


INTRODUCTION
A new notice type has been added to GCN that allows users
to monitor the connectivity and delivery time of Notices
from GCN to themselves.  The new notice type is called DOW_TOD_TEST
(Day of Week Time of Day).  It will be sent at the time you
request on the days you request.

PURPOSE/MOTIVATION:
There are two motivations (uses) for this notice type:
1) It allows email-based customers to do a spot-check
on their connectivity (this is particularly useful
for cellphone-based customers).  (Socket-based customers
already have this connectivity capability via the Imalive packets.)
2) It allows the recipient to periodically determine the time delay
of the total delivery system.  GCN does this by creating and sending
a special notice at the time-of-day you request (the notice
has the creation date/time_stamp in the notice).  Then you can look
at the receive time to see how many seconds have elapsed.
(For email-based customers, the top-most "Received:" line
in the email full-header has the timestamp at the final destination
computer (your computer).)  (The GCN computer is slaved
to a Network Time Server machine and is never more than 200 msec off of UT;
typically not more than 60 msec.  Is your computer slaved
to a time-server?  Also be aware that mail-agents only check/fetch
for "new mail" on a periodic basis (eg every 60 sec), so that will
cause additional (sometimes long) delivery delays.)

FORMAT:
The specification to enable this notice type is a little different
than the specifications for the regular GRB/Transient notice types.
For DOW_TOD_TEST notices, the entry in your configuration will look like:
    DOW_TOD_TEST 0x7F,12:00
This particular entry would result in a DOW_TOD_TEST notice
being sent every day (Sun through Sat) at 12:00:00 UT.
The first part (0x7F) is a bit mask to select the day(s) of the week
you want to receive the notice (Sun is 2^0 and Sat is 2^6).
The second part (12:00) is the hour and minute of the day you want to receive.
If you just wanted to receive them only on Tuesdays at 20:35:00 UT,
the entry would be:
    DOW_TOD_TEST 0x04,20:35
Weekdays at 16:00 would be:
    DOW_TOD_TEST 0x3E,16:00
Fridays at 16:00 would be:
    DOW_TOD_TEST 0x20,16:00

ACCURACY OF THE CREATE TIME:
The specific notice for each customer is created within 2 sec (85 percentile)
of the time requested (eg 20:35 would have the notice created
between 20:35:00.0 and 20:35:01.99 UT)
Of course, this is dependant on the load on the GCN computer.
Based on trial runs of 114 notices over 5 days of testing,
the distribution of deviations from the specified creation times
ranged from 1 to 5 sec (mean of 1.2 sec).
Of course, because the actual creation timestamp is in each notice,
you will always be able to determine the delivery delay.

DISTRIBUTION METHODS:
This notice is available via all the distribution methods within GCN:
full-format email, all 4 cell/pager formats, XML email, and
socket (160-byte binary and VOEvent XML).
GCN will use the distribution method/format for which your site is
already configured.

MORE INFORMATION:
Can be found at: http://gcn.gsfc.nasa.gov/gcn/dow_tod.html

NOTICE EXAMPLE:
Here is an example of a full-format email DOW_TOD_TEST Notice:
    TITLE:        GCN/DOW_TOD_TEST Check Notice
    NOTICE_DATE:  Mon 30 May 11 22:35:01 UT
It is much shorter than the regular full-format email notices,
but it contains all that is needed for this function.
The socket packets contents can be found at:
http://gcn.gsfc.nasa.gov/gcn/sock_pkt_def_doc.html

FINAL COMMENT:
Socket sites are already accustomed to being able to monitor
their delivery delays via the Daily_Socket_Connection Reports
which contain a histogram of the round-trip delivery times
for all the packets they are sent and that they echo back to GCN.
So this DOW_TOD_TEST notice is designed primarily for the email-based
customers, but any site can sign up for it.

ACTION ITEM:
If you want to receive this DOW_TOD_TEST notice type,
please send me a request to have them enabled,
along with which days of the week you want to receive them
and at what time of day.
You can do this by forwarding this email with your request to:
scott@milkyway.gsfc.nasa.gov   (since it already has your "site name").
Or you can use the "Modify Site (#2)" option at:
http://gcn.gsfc.nasa.gov/gcn/config_builder.html .
There is a place on that webform page to click the days-of-the-week
and to enter a time-of-day.

REMINDER OF RECENT ADDITIONS TO GCN:
In case you have missed them, here is a brief list of the most recent
additions to the GCN system.  You might consider signing up
for these Notice types as well:
FERMI_GBM FIN_POS  (1 week ago)  // Human-in-the-loop ground-based analysis
MAXI_UNKNOWN/_KNOWN (Apr 2011)   // Unknown transients & Flare-ups from Known sources
INTEGRAL_WEAK  (Feb 2011)        // Subthreshold detections by INTEGRAL
SWIFT_BAT_MONITOR (Feb 2010)     // Flare-ups from known sources monitored by Swift-BAT


Sincerely,
Scott

Scott Barthelmy                      NASA-GSFC, Code 661, Greenbelt, MD   20771
PHONE:  301-286-3106                 (office)       CELL:   301-346-3733
FAX:    301-286-1684                 (1st choice,  -1682 2nd choice)
EMAIL:  scott@lheamail.gsfc.nasa.gov
PAGER:  3013463733@cingularme.com
WEB:    http://gcn.gsfc.nasa.gov/gcn